The goal of this program is to create miniature, low-power neural signal recording and stimulation systems that can be controlled by short range (<10m) telemetry for neuropsychological experiments. These systems will be integrated into head-mounted packages and provide untethered recording and stimulation interfaces for up to 128 extracellular electrodes for animals as small as mice and rats. The systems will consist of recently developed VLSI neural signal amplifier and stimulation components, and commercial, off-the-shelf analog-to-digital converters, programmable logic, and telemetry components. In Phase I of this program, we will investigate the feasibility of 3 different telemetry modes: (1) Infrared serial data, (2) Frequency Shift Keying (FSK) modulated RF in the 900 MHz and 2.4GHz ISM bands, (3) Ultra-Wide Band (UWB) modulated RF in the 3.1GHz to 10.6GHz UWB communications band. This phase will include parametric testing of commercially available parts for these telemetry modes and testing of prototype systems to investigate telemetry performance and interference with neural recording. In Phase II of this program, we will select the best telemetry modules and develop the final head-mounted systems and all of the external support hardware and software for using these systems in neurophysiological experiments. These external components will include the telemetry base stations and a flexible digital I/O interface for data acquisition and stimulation control along with Graphical User Interface software to control the system configuration.